The present invention relates to individual equipment for protecting personnel exposed to so-called NBC threats (nuclear, bacteriological, or chemical contamination).
Such individual equipment generally comprises a helmet, a full face cover provided with fastenings for fixing it to the helmet and with a coupling for a breathing gas feed or ventilation hose, and a flexible envelope, often called a neck gasket, for extending the helmet and the face-cover downwards, together with airtight connection means between the helmet, the face-cover, and the envelope. The helmet provides protection against puncture and shock, and also serves as a support for various items such as earphones and a transparent visor.
That structure makes it possible for personnel to use only the helmet when performing a mission that does not include any NBC threat. This avoids the discomfort of items of equipment that envelop the face and the neck completely.
However, when personnel is informed prior to a mission that there is a risk of an NBC attack, then the envelope is installed on the helmet. When the actual presence of a threat is indicated, either by sensor means carried by a vehicle occupied by personnel, or by transmitted information, then the user dons the face cover and secures it to the helmet, after switching on the ventilation system that feeds filtered air or the system for feeding breathing gas.
The first situation arises in particular in helicopters that operate at low altitude and that are therefore not fitted with a pressurized oxygen source, and also on military transport planes operating at moderate altitude.
The structure of the equipment as three separate items (helmet, face-cover, and envelope) suffers from the point of view of gastightness from the drawback of having a point of interconnection between all three items. It is difficult to provide the amount of sealing necessary for protection purposes at this "triple" point.